Photoinduced electron transfer mediated by a hydrogen-bonded interface

Turró, Claudia; Chang, C. K.; Leroi, G. E.; Cukier, Robert I.; Nocera, Daniel G.

doi:10.1021/ja00036a081

Cited by 242 publications

(153 citation statements)

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“…PCET is triggered by laser excitation of the donor or acceptor and resolved kinetically by performing time-resolved spectroscopy. These systems have provided tangible kinetics benchmarks for PCET reactions (Turró et al 1992; Kirby et al 1995Kirby et al , 1997Roberts et al 1995Roberts et al , 1997Deng et al 1997;Yeh et al 2001b;Damrauer et al 2004) and stimulated the development of theories to describe PCET (Cukier & Nocera 1998;Hammes-Schiffer 2001a,b).…”

Section: Proton-coupled Electron Transfer Model Systemsmentioning

confidence: 99%

“…, DZzinc(II) porphyrin, AZdinitrobenzene) exploited the propensity of carboxylic acids to form cyclic dimers in low polarity, non-hydrogen bonding solvents (Turró et al 1992). Observation of a deuterium isotope effect for charge separation and recombination revealed the coupling between electron and proton.…”

Section: Proton-coupled Electron Transfer Model Systemsmentioning

confidence: 99%

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Proton-coupled electron transfer: the mechanistic underpinning for radical transport and catalysis in biology

Reece

Hodgkiss

Stubbe

et al. 2006

Phil. Trans. R. Soc. B

264

340

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Charge transport and catalysis in enzymes often rely on amino acid radicals as intermediates. The generation and transport of these radicals are synonymous with proton-coupled electron transfer (PCET), which intrinsically is a quantum mechanical effect as both the electron and proton tunnel. The caveat to PCET is that proton transfer (PT) is fundamentally limited to short distances relative to electron transfer (ET). This predicament is resolved in biology by the evolution of enzymes to control PT and ET coordinates on highly different length scales. In doing so, the enzyme imparts exquisite thermodynamic and kinetic controls over radical transport and radical-based catalysis at cofactor active sites. This discussion will present model systems containing orthogonal ET and PT pathways, thereby allowing the proton and electron tunnelling events to be disentangled. Against this mechanistic backdrop, PCET catalysis of oxygen-oxygen bond activation by mono-oxygenases is captured at biomimetic porphyrin redox platforms. The discussion concludes with the case study of radical-based quantum catalysis in a natural biological enzyme, class I Escherichia coli ribonucleotide reductase. Studies are presented that show the enzyme utilizes both collinear and orthogonal PCET to transport charge from an assembled diiron-tyrosyl radical cofactor to the active site over 35 Å away via an amino acid radical-hopping pathway spanning two protein subunits.

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Section: Proton-coupled Electron Transfer Model Systemsmentioning

confidence: 99%

Section: Proton-coupled Electron Transfer Model Systemsmentioning

confidence: 99%

Proton-coupled electron transfer: the mechanistic underpinning for radical transport and catalysis in biology

Reece

Hodgkiss

Stubbe

et al. 2006

Phil. Trans. R. Soc. B

264

340

View full text Add to dashboard Cite

show abstract

“…The importance of the pathways that cross from the Met121 strand to the Cys112 strand depends upon the coupling ef®ciencies of the hydrogen bonds. Model-complex studies have demonstrated ef®cient electron transfer across hydrogen-bonded interfaces [69,70]. In the standard Beratan-Onuchic pathway model, hydrogenbond couplings are distance-scaled and generally afford weaker couplings than covalent bonds [53].…”

Section: Tunneling Timetablesmentioning

confidence: 99%

Electron tunneling in biological molecules

Winkler¹,

Bilio²,

Farrow³

et al. 1999

Pure and Applied Chemistry

141

185

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Electron transfers in photosynthesis and respiration commonly occur between protein-bound prosthetic groups that are separated by large molecular distances (often greater than 10 A Ê ). Although the electron donors and acceptors are expected to be weakly coupled, the reactions are remarkably fast and proceed with high speci®city. Tunneling timetables based on analyses of Fe 2 /Cu to Ru 3 electron-transfer rates for Ru-modi®ed heme and copper proteins reveal that the structure of the intervening polypeptide can control these distant donor±acceptor couplings. Multistep tunneling can account for the relatively rapid Cu to Re 2 electron transfer observed in Re-modi®ed azurin.

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“…To mimic natural processes, various supramolecular model systems assembled via hydrogen bonding [5][6][7][8][9][10] have been developed, and electron transfer process in these systems has been extensively examined by several groups. Nocera and coworkers 11 initially reported the intramolecular electron transfer in a carboxyl hydrogen bonding connected porphyrin/dinitrobenzene dyad. Sessler et al 12,13 developed a non-covalently assembled supramolecular system based on Watson-Crick-type nucleic acid base pairing interactions, and the hydrogen bonds provided an effective pathway for mediating the electron transfer process.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Electron Transfer within Porphyrin‐Anthra‐quinone Dyads Connected by Hamilton Hydrogen Bonding

Zhao

Chen²,

Zeng

et al. 2010

Chin. J. Chem.

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Porphyrin-or zinc-porphyrin-cyanuric acid conjugants (TPP-CA or ZnTPP-CA) and anthraquinone connected with the known "Hamilton receptor" (AQ-H) were synthesized. The supramolecular dyads constructed via the AQ-H and TPP-CA/ZnTPP-CA exhibit six hydrogen bonds, which provide the association constant K APP approximately (2.8±0.3)×10 3 mol -1 •L in toluene. Selective excitation of the porphyrin/zinc porphyrin chromophores results in an electron transfer between TPP-CA/ZnTPP-CA and AQ-H within the supramolecular assemblies, leading to an efficient quenching of the TPP-CA/ZnTPP-CA fluorescence. The singlet electron transfer from porphyrin/ zinc-porphyrin to anthraquinone proceeds mainly via a 'through space' mechanism with efficiencies of 43%, 58%, and rate constants of 7.6×10 7 , 7.0×10 8 s -1 , respectively.

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Photoinduced electron transfer mediated by a hydrogen-bonded interface

Cited by 242 publications

References 0 publications

Proton-coupled electron transfer: the mechanistic underpinning for radical transport and catalysis in biology

Proton-coupled electron transfer: the mechanistic underpinning for radical transport and catalysis in biology

Electron tunneling in biological molecules

Photoinduced Electron Transfer within Porphyrin‐Anthra‐quinone Dyads Connected by Hamilton Hydrogen Bonding

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